The present invention relates to a pickup feed mechanism for feeding a pickup capable of recording and reproducing optical information, and more particularly to a pickup feed mechanism used with a disc having information recorded on both sides.
Currently, a disc-shaped optical information medium is installed to be rotated in such widespread devices such as a compact disc player, a video disc player, a CD ROM drive, a magneto-optical disc device, etc. An optical pickup scans the disc with an optical beam, detects a reflected modulated light, and moves in a predetermined range to reproduce and record the information on the disc. Here, the optical pickup is installed to reciprocate along a radius of the disc or a curve within the radius. Accordingly, in the case of a disc with optical information on both sides, after the information on one side has been reproduced (or recorded), the disc needs to be reversed to operate on the other side.
However, Japanese laid-open patent publication Nos. Sho 63-302479 and Hei 2-21469 disclose that the disadvantage of individually reversing the dual-sided disc can be removed by utilizing a pickup feed mechanism having an U-shaped moving interval with a radius range of both sides of to the dual-sided reproducible disc. This is structured in such a way that a motor is installed in a pickup, a U-shaped rack gear member is always engaged with a gear driven by the motor, and two guide shafts penetrate and support the pickup during intervals where the pick up travels in the same direction as the surface of the disc. That is, after ending the reproducing for the one side of the disc, the pickup is separated from one of the two guide shafts and is invested by a U-turn along the rack gear member, and is then combined with the other guide shaft, thereby being moved to a position to reproduce the other side of the disc. However, in this structure, while the pickup is moved to invert its direction, it is moved without being connected to either of two guide shafts, so that there is a problem such that the left/right balance of the pickup is unstable. Accordingly, after the movement of directional inversion, there often occurs a problem that the pickup is not connected to the guide shaft. The solution to the above problems requires a complex, errorless, and highly accurate structure, e.g., the installation of a gear and a rack gear member on the left and right sides, but it is very expensive and creates manufacturing difficulties.